Preeclampsia (also known as toxemia) is a life-threatening condition that affects pregnant women, usually late in the second or third trimester, and postnatal women in the first six weeks after delivery. It is diagnosed by new onset protein in the urine (proteinuria) and high blood pressure. The condition affects the kidneys, liver, brain, heart and placenta of the pregnant woman. Preeclampsia occurs in approximately eight to ten percent of pregnancies and is only alleviated by ending the pregnancy, either by induction of labor or cesarean. Its cause is still largely unknown. Preeclampsia most commonly occurs during a first pregnancy. The risk for preeclampsia is also known to be moderately increased for certain groups of pregnant women, including women who are over 35 years of age or under 18 years of age; women who are genetically predisposed to this condition; women who suffer from preexisting hypertension, diabetes, autoimmune diseases like lupus, various inherited thrombophilias like Factor V Leiden, or renal disease; obese women, and in women with multiple gestations (twins, triplets, and more). The single most significant risk for developing preeclampsia is having had preeclampsia in a previous pregnancy.
Although preeclampsia usually develops after the twentieth week of pregnancy, it can also begin earlier, if there is a hydatiform mole. Preeclampsia can develop either gradually or suddenly, and may remain mild throughout the pregnancy or become severe. Common symptoms in addition to high blood pressure and proteinuria are elevated uric acid, vision problems such as blinking lights or blurry vision, persistent headaches, extreme swelling of hands and feet, fluid retention, pain in the upper right abdomen. If untreated, preeclampsia can damage the mother's liver or kidneys, deprive the fetus of oxygen, and cause eclampsia (seizures). A pregnant woman with signs of preeclampsia must be closely monitored by a physician. Moderate to severe preeclampsia is often treated in the hospital with bed rest, magnesium sulfate, and medication for high blood pressure. Unfortunately, delivery is still the only true “cure” for preeclampsia. In fact, when a woman has severe preeclampsia or is near term with mild to moderate preeclampsia, delivery is still the best remedy to date. Labor is then started with medication, unless a cesarean section is deemed necessary. Within the first few days following delivery, the mother's blood pressure usually returns to normal, however, with severe preeclampsia, it may take several weeks for blood pressure to return to normal.
Specifically, preeclampsia is diagnosed when a pregnant woman develops high blood pressure (two separate readings taken at least four hours apart of 140/90 mm Hg or more) and 300 mg of protein in a 24-hour urine sample (i.e., proteinuria). Swelling or edema, (especially in the hands and face) was long considered an important sign for a diagnosis of preeclampsia, but in today's medical practice only hypertension and proteinuria are necessary for a diagnosis, because up to 40% of women with normal pregnancy can also have edema. However, pitting edema, i.e., unusual swelling, particularly of the hands, feet, or face, which is notable by leaving an indentation when pressed on, can be significant and must be reported to a physician. Although eclampsia is potentially fatal, preeclampsia may be overtly asymptomatic, or may present with symptoms of typical pregnancy-associated ailments. The epigastric pain, for example, which reflects hepatic involvement and is typical of a severe form of preeclampsia termed the HELLP syndrome (i.e., hemolysis, elevated liver enzymes and low platelets) can easily be confused with heartburn, a very common problem of pregnancy. Presumptive diagnosis of preeclampsia, therefore, is dependent upon coincident preeclamptic features, with definitive diagnosis generally not possible until symptom regression after delivery is observed.
Although advances have been made in the realm of preeclampsia screening, clinicians continue to grapple with optimal strategies to monitor pregnant women who are at risk for preeclampsia. An approach that protects both mother and child from the harmful effects of preeclampsia is desired. The present disclosure addresses this need by providing methods for determining whether a pregnant woman has or is predisposed to preeclampsia.